In the case of aimraft, the drive system for the leading edge flaps is known to require a failure protection unit at each wing tip. This failure protection unit, which is sometimes called an asymmetry brake, is needed to stop rotation of the drive system in the event of a drive failure. As is also known, the failure protection unit must not engage during normal operation but must engage rapidly in the event of a shaft overspeed condition.
Generally speaking, it is known that the leading edge flaps on aircraft are basically quite unstable in nature. The wings, of which they form a part, are also known to be quite thin which means that there is a small envelope for positioning a failure protection unit. Moreover, it is known that typical air loads may cause a leading edge flap to be driven out of position quite rapidly.
In order to be acceptable, a failure protection unit must satisfactorily deal with all of these problems. It is also a typical requirement to be able to engage a failure protection unit, or asymmetry brake, in response to an electrical signal received from the flight computer. However, in any case, the dynamic torque during lockup must not exceed the shaft torque capacity.
From the foregoing, it will be appreciated that the primary requirements for a failure protection unit are rather well known. The unit must engage rapidly in the event of shaft overspeed, or in response to an electrical signal. There must also be an avoidance of inadvertent trips and the failure protection unit must therefore be insensitive to normal shaft acceleration. The unit must also limit shaft torque during engagement, and be easily resettable by ground maintenance personnel. Unfortunately, the failure protection units that have heretofore been available are less than entirely satisfactory.
The present invention is directed to overcoming one or more of the foregoing problems and achieving one or more of the resulting objects.